The answer is that the client certificates lack the Client Authentication extended key usage (EKU). EAP-TLS requires the client to present a certificate that ISE can validate for the purpose of proving its identity; if the certificate is missing the Client Authentication EKU, ISE will reject it even if the certificate is otherwise trusted and present in the personal store. On the Cisco SCOR 350-701 exam, this scenario tests your understanding of how EAP-TLS certificate authentication works with ISE, specifically the role of EKUs in certificate selection and validation—a common trap is assuming any valid certificate will work, when in fact the EKU must explicitly match the intended use. Remember the mnemonic: “No Client Auth EKU? No network for you.”
350-701 Practice Question: Secure Network Access, Visibility and Enforcement
This 350-701 practice question tests your understanding of secure network access, visibility and enforcement. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A multinational corporation is implementing ISE for wired network access using 802.1X with EAP-TLS certificate authentication. Their Windows 10 laptops have certificates issued by an internal PKI. During testing, some users report that they are repeatedly prompted to select a certificate after connecting, and eventually authentication fails. ISE logs show 'Authentication failed - No matching certificate found'. The engineer checks the client machine and sees multiple certificates, including the correct one, in the personal store. The ISE endpoint identity store is populated with the user's AD credentials. What is the most likely cause of this failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The client certificates lack the 'Client Authentication' extended key usage (EKU)
EAP-TLS requires the client to send a certificate that ISE can validate. If the client does not automatically select the correct certificate due to multiple certificates, and ISE receives the wrong one, it may reject if that certificate is not trusted for client authentication. Option A is correct because the client may not have a certificate with the proper EKU (Client Authentication) that matches the ISE configuration. Option B would cause other errors. Option C is possible but not the primary cause. Option D would affect all users but not specific.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The client's certificate is expired
Why it's wrong here
Expired certificate would be rejected with a different reason.
✗
The Windows supplicant requires a registry modification to enable auto-selection
Why it's wrong here
While this could cause prompt, the ultimate failure reason would still be certificate mismatch.
✗
ISE trusted CA certificate list does not include the issuing CA
Why it's wrong here
If the CA was not trusted, ISE would refuse all certificates from that CA, not just some.
✓
The client certificates lack the 'Client Authentication' extended key usage (EKU)
Why this is correct
EAP-TLS requires a certificate with Client Authentication EKU; if missing, ISE will not accept it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-701 NAT questions on configuration and troubleshooting.
Secure Network Access, Visibility and Enforcement — This question tests Secure Network Access, Visibility and Enforcement — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The client certificates lack the 'Client Authentication' extended key usage (EKU) — EAP-TLS requires the client to send a certificate that ISE can validate. If the client does not automatically select the correct certificate due to multiple certificates, and ISE receives the wrong one, it may reject if that certificate is not trusted for client authentication. Option A is correct because the client may not have a certificate with the proper EKU (Client Authentication) that matches the ISE configuration. Option B would cause other errors. Option C is possible but not the primary cause. Option D would affect all users but not specific.
What should I do if I get this 350-701 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-701 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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